The present invention relates to a projection type display device projecting an image onto a screen by using a light valve element such as a liquid crystal panel or the like. Examples of industrial applications of such a device include a liquid crystal projection type display device, a liquid crystal television set, and a projection type display device.
Conventionally known is a projection type projector, such as a liquid crystal projector or the like. The projector projects an image in an enlarged scale onto a screen by changing light from an electric bulb or other light source into a specific shade of gray for each pixel using a light valve element such as a liquid crystal panel.
The conventional projection type display device works as follows. An optical modulator as light valve means modulates light from a lamp as a light source of illuminating means. Projecting means then projects the light onto a screen or the like to display the same as an image. In a projection type display device of this type, it is common practice to provide cooling means for exhausting out of the unit components of heat generated from sources other than a light output produced by the lamp as the illuminating means. In the meantime, the optical modulator as the light valve means absorbs unwanted light or otherwise generates heat when the modulator converts the light through modulation to a corresponding image. It is known that failure, at this time, to provide temperature control for the optical modulator results in the life of the modulator being shortened. It is therefore common practice also to provide cooling means for the light valve element.
Prior art approaches toward an exhaust direction in such a projection type display device are disclosed, for example, in Japanese Patent Laid-open No. Hei 9-319007, Japanese Patent Laid-open No. 2000-137291, and Japanese Patent Laid-open No. 2001-185884.
The prior art disclosed in Japanese Patent Laid-open No. Hei 9-319007 has the following arrangement. Specifically, a flexible duct is provided at an exhaust port of the projection type display device and the direction of the duct is changed as necessary. Such an arrangement allows the exhaust direction to be appropriately varied according to environmental conditions at an installation site. The need to vary the exhaust direction in response to the installation site environment is thus satisfied.
The prior art disclosed in Japanese Patent Laid-open No. 2000-137291 provides an arrangement that allows the exhaust direction to be appropriately changed. Specifically, a directing direction of an exhaust guide (louver) provided at an exhaust port is appropriately changed to direct an exhaust heat in either an upward or a downward direction, or a rightward or a leftward direction. Such an arrangement allows the exhaust direction to an outside of the unit to be appropriately varied. The need to vary the exhaust direction in response to the installation site environment is thus satisfied to a degree.
The prior art disclosed in Japanese Patent Laid-open No. 2001-185884 provides the following arrangement. Specifically, a plurality of exhaust ports facing in different directions are provided. A sensor mounted in each of the plurality of exhaust ports detects a plugged port. Different exhaust ports are used so as to avoid the plugged port or ports. Such an arrangement meets the need to vary the exhaust direction in response to the installation site environment.